Apparatus and method for a mobile telecommunications system

ABSTRACT

An apparatus comprising circuitry configured to perform a Random Access procedure that is based on one or more access control parameters that are specific for a predefined coverage level.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.16/496,454, filed Sep. 23, 2019, which is based on PCT FilingPCT/EP2018/058105, filed Mar. 29, 2018, which claims priority to EP17164062.6, filed Mar. 31, 2017, the entire contents of each areincorporated herein by reference.

TECHNICAL FIELD

The present disclosure generally pertains to entities and user equipmentof a mobile telecommunications system.

TECHNICAL BACKGROUND

Long Term Evolution (“LTE”) is a candidate for providing therequirements of 5G, which is a wireless communication technologyallowing high-speed data communications for mobile phones and dataterminals and which is already used for 4G mobile telecommunicationssystems. Other candidates for meeting the 5G requirements are termed NewRadio Access Technology Systems (NR).

An NR can be based on LTE technology, just as LTE was based on previousgenerations of mobile communications technology. LTE is based on theGSM/EDGE (“Global System for Mobile Communications”/“Enhanced Data ratesfor GSM Evolution” also called EGPRS) of the second generation (“2G”)and UMTS/HSPA (“Universal Mobile Telecommunications System”/“High SpeedPacket Access”) of the third generation “3G”) network technologies. LTEis standardized under the control of 3GPP (“3rd Generation PartnershipProject”). There exists a successor LTE-A (LTE Advanced) allowing higherdata rates than the basic LTE which is also standardized under thecontrol of 3GPP. For the future, 3GPP plans to further develop LTE-Asuch that it will be able to fulfill the technical requirements of 5G.

The term “Internet of things” (IoT) denotes the inter-networking ofphysical devices, vehicles, buildings, and other items that are providedwith electronics, software, sensors, actuators, and network connectivitythat enable these objects to collect and exchange data. Such objects arealso referred to as “connected devices” and “smart devices”.

Machine-type Communication (MTC) enables IoT devices to exchangeinformation in an autonomous way without human intervention. 3GPP is inthe process of improving LTE networks for Machine-type Communication(MTC). Examples are enhanced NB-IoT (eNB-IoT) with new power classes,improved mobility support and multicast messaging, or furtherenhancements for eMTC (feMTC) including VoLTE support and multicastmessaging. These improvements are the next steps in the direction of 5Gnetworks for massive MTC (mMTC).

eMTC (enhanced Machine Type Communication) is a 3GPP IoT technology thatsupports low-cost and high coverage for such machine-type communicationdevices. The technology is based on Long Term Evolution (“LTE”) and eMTCdevices are supported within an LTE host carrier.

With Release 13 of the 3GPP standards LTE-M has been developed for LTEM2M communications. LTE-M introduces new categories known as LTE Cat 1.4MHz and LTE Cat 200 kHz.

Although there exist signaling techniques for Machine-type Communication(MTC), it is generally desirable to improve the signaling in suchtechnologies.

SUMMARY

According to a first aspect, the disclosure provides an apparatusincluding circuitry configured to perform a Random Access procedure thatis based on one or more access control parameters that are specific fora predefined coverage level.

According to a further aspect, the disclosure provides an apparatusincluding circuitry configured to broadcast access control parametersthat are specific for a predefined coverage level.

According to a further aspect, the disclosure provides a methodincluding performing a Random Access procedure that is based on one ormore access control parameters that are specific for a predefinedcoverage level.

According to a further aspect, the disclosure provides a computerprogram including instructions, the instructions when executed on aprocessor performing a Random Access procedure that is based on one ormore access control parameters that are specific for a predefinedcoverage level.

Further aspects are set forth in the dependent claims, the followingdescription and the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments are explained by way of example with respect to theaccompanying drawings, in which:

FIG. 1 schematically shows the access barring check defined in TS36.331;

FIG. 2 shows an embodiment of an extended SIB2 information that includesaccess class barring parameters for per CE level access barring;

FIG. 3 shows an example of an erroneous CE level judgement;

FIG. 4 shows the aspect of CE level “reselection” of the RACH procedureas defined in the standard;

FIG. 5 shows an embodiment of a modified RACH procedure;

FIG. 6 shows an embodiment of a modified access barring check;

FIG. 7 shows an embodiment of a two stage access class barring per CElevel;

FIG. 8 shows an embodiment in which a higher accurate RSRP measurementis performed if the AC barring parameters are set for a particular CElevel; and

FIG. 9 shows an embodiment of a general purpose computer that canfunction as any type of apparatus or entity, base station or new radiobase station, transmission and reception point, or user equipment asdescribed herein.

DETAILED DESCRIPTION OF EMBODIMENTS

Before a detailed description of the embodiments under reference of FIG.1, general explanations are made.

The embodiments relate to an apparatus including circuitry configured toperform a Random Access procedure that is based on one or more accesscontrol parameters that are specific for a predefined coverage level.

An apparatus as described in the embodiments may for example be a mobiletelecommunications system entity, in particular user equipment, a MTCUE, a base station (eNodeB), or the like. In particular, an apparatusincluding circuitry configured to perform a Random Access procedure maybe a UE or a MTC UE.

An apparatus as described in the embodiments may for example be a 3GPPcompliant communication device, e.g. an LTE or advanced LTE type device.The apparatus may for example provide the requirements of 5G or otherNew Radio Access Technology Systems (NR).

Circuitry may include at least one of: processor, microprocessor,dedicated circuit, memory, storage, radio interface, wireless interface,network interface, or the like, e.g. typical electronic components whichare included in a base station, such as an eNodeB.

An apparatus including circuitry configured to perform a Random Accessprocedure may for example allow for a coverage level based access classbarring.

A coverage level may for example be any information that groupsmeasurements (e.g. Reference Signal Received Power (RSRP) measurements)of a user equipment into predefined subsets, so that a user equipmentcan be attributed to one of the subsets according to its measurementresult. A coverage level may for example be a CE level that is definedin the LTE standard. There may for example be four predefined coveragelevels, such as CE level 0, CE level 1, CE level 2 and CE level 3.Coverage levels may be standard or enhanced coverage levels.

Coverage levels may also be attributed to coverage modes. For examplecoverage levels such as CE level 0 and CE level 1 may be attributed to aCE mode A, whereas coverage levels such as CE level 2 and CE level 3 maybe attributed to a CE mode B, where CE mode A relates to shallowcoverage and CD mode B relates to deep coverage. Deep coverage may inparticular relate to UEs or MTE UEs that are located inside ofbuildings.

As far as the embodiments speak about parameters that are “specific fora predefined coverage level” or “coverage-specific”, this may forexample refer to parameters that are defined for a specific coveragelevel (e.g. CE level) or this may refer to parameters that are definedfor a specific coverage mode (e.g. CE mode).

Access control parameters may be any parameters that are intended tocontrol the access of user equipment to communication channel such as aRandom Access Channel (e.g. RACH, PRACH) or other resources such as adata channel. Access control parameters may for example relate totechniques for access control such as Access Class Barring (ACB),Extended Access Barring (EAB), or Application specific Congestioncontrol for Data Communication (ACDC).

The embodiments disclosed below may apply access barring mechanisms indeep coverage. This may permit a usage of different network policies.Also, the embodiments as described below may result in an improvedaccess/load control of idle mode UEs.

According to embodiments, the circuitry is configured to receive, forone or more predefined coverage levels (e.g. CE level 0, CE level 1, CElevel 2, CE level 3), one or more access control parameters that arespecific for the respective coverage level.

For example, the circuitry may read the coverage level specificparameters from system information, e.g. from an extended SystemInformation Block 2 (SIB2). A SIB2 extension may for example include perCE level access barring parameters for RA resources and other networkresources.

According to embodiments, the circuitry is configured to apply thecoverage-specific access control parameters based on its coverage level.For example, a UE may select and apply those coverage-specific accesscontrol parameters that are attributed to its own coverage level.

The circuitry may be configured to determine its (respectively a UE's)coverage level by measurement. A measurement may for example be an RSRPmeasurement and a coverage level may be determined based on RSRPmeasurements by e.g. computation.

According to embodiments, there are four predefined coverage levels(e.g. CE level 0, CE level 1, CE level 2, CE level 3) and/or there aretwo predefined coverage modes (e.g. CE mode A, CE mode B). Such coveragelevels and/or coverage modes may for example be defined in a standard,e.g. in the LTE standard.

The circuitry may be configured to perform a modified Random Access (RA)procedure in deep coverage and to take coverage level specific accessbarring parameters into account.

Coverage-specific access control parameters may for example include acoverage-specific barring factor (ac-BarringFactor), a coverage-specificbarring time (ac-BarringTime), and/or coverage-specific access classbits (ac-BarringForSpecialAC). The coverage-specific access controlparameters may for example include an ac-BarringFactor that controls arandom number test of a random access procedure. Still further, thecoverage-specific access control parameters may include a parameterac-BarringTime that is used to calculate the barring time tbarring.Still further, the coverage-specific access control parameters mayinclude a parameter that includes access class bits which control accessof UEs on a per CE level basis (e.g. ac-BarringForSpecialAC for specialaccess classes 11 . . . 15).

According to embodiments, the circuitry is configured to perform acoverage level reselection process. The apparatus may for exampleperform the coverage level reselection process if no Random AccessResponse is received within the RA Response window, or if the RandomAccess Response reception is considered not successful.

The circuitry may for example be configured to perform, during thecoverage level reselection process, an access barring check for aspecific coverage level.

For example, the circuitry may be configured to perform the accessbarring check when the coverage level changes during a Random Accessprocedure.

The circuitry may be configured to, if the access barring check for thespecific coverage level is not successful, wait for the barring timerfor this coverage level to expire and the circuitry may be configuredto, if the access barring check for the specific coverage level issuccessful, select a Random Access Preambles group, a Response WindowSize, a Contention Resolution Timer, and/or a PRACH resourcecorresponding to the selected enhanced coverage level.

Such an access barring check may be performed on the MAC layer.

According to embodiments, the circuitry is configured to terminate abarring timer when the coverage level changes.

The circuitry may be configured to perform RA access barring and, ifsuccessful, then perform other resource barring. For example, in a firststage, RA resource barring is checked before initiating the RAprocedure; and if it is determined that RA resources are not congestedthen the UE performs the RA procedure and determines its accuratecoverage level and does not apply access barring in the middle of the RAprocedure. Once the coverage level has been determined, then the UEperforms the access barring check for the accurate coverage level beforesending the RRC connection Request or Msg3. Thus, RRC and MAC layerindependence may be maintained.

According to embodiments, the circuitry is configured to perform ahigher accurate RSRP measurement if AC barring parameters are set for aparticular coverage level. For example, an indication to perform precisemeasurements in order to determine an accurate coverage level may beused and corresponding barring parameters may be applied.

The embodiments also disclose an apparatus including circuitry that isconfigured to broadcast access control parameters that are specific fora predefined CE level. Such an apparatus may for example be a networkentity such as a base station (eNodeB, eNB), or the like. The circuitryof such an apparatus may be configured to choose the access controlparameters such that coverage level access barring prefers deep coverageUEs over shallow coverage UEs.

The circuitry may also be configured to apply coverage-specific accessclass barring to RA resources only. Accordingly, CE level access barringmay allow deep coverage UEs, if operators are interested in creatingextra revenue from deep coverage UEs, and in this case the network may,in case of congestion, bar more of the shallow coverage UEs.

The embodiments also disclose a method including performing a RandomAccess (RA) procedure that is based on one or more access controlparameters that are specific for a predefined coverage level.

The embodiments also disclose a computer program including instructions,the instructions when executed on a processor performing a Random Access(RA) procedure that is based on one or more access control parametersthat are specific for a predefined coverage level.

The embodiments also disclose a machine-readable medium storing such acomputer program.

LTE Access Class Barring

The Random Access Channel (RACH) is a common transport channel in theuplink that is mapped one-to-one onto physical channels (PRACHs). Themain purpose of Random Access Procedure is to achieve uplinksynchronization and to obtain a grant for initial attach.

When UE sends the very first message of random access procedure to somenetwork, it basically sends a specific pattern or signature which iscalled RACH preamble. The preamble value differentiate requests comingfrom different UEs. If two UEs use the same RACH preambles at the sametime then there can be collision. To resolve the problem of RAcongestion in LTE systems, different solutions are applied.

Basic information about the Random Access Procedure such as accessbarring parameters are informed to a UE via SIB2. If access barringparameters are broadcasted in SIB2 and UE has associated access class (0. . . 15 whereby 0 . . . 9 are normal ACs and 10 and beyond are specialACs.), which is currently barred, then the UE draws a random number andcompares it with a broadcasted barring factor value. If the number ishigher than the broadcasted value, then the UE considers access to thecell is barred otherwise access is not barred. This is specified insection 5.3.3.11 “Access barring check” of [1] (TS 36.331).

FIG. 1 schematically shows the access barring check defined in section5.3.3.11 “Access barring check” of [1] (TS 36.331). At 101 it is testedif a timer T302 or “Tbarring” is running. If yes, the process proceedsat 102, if no, the process proceeds at 103. At 102, access to the cellis considered as barred. At 103, it is tested if SIB2 includes theinformation element “AC barring parameters”. If yes, the processproceeds at 104, if no, the process proceeds at 107. At 104, it istested if the UE has one or more Access Classes as stored on the USIMwith a value in the range 11 . . . 15, which is valid for the UE to useaccording to TS 22.011 [3] and TS 23.122 [4] (ACs 12, 13, 14 are onlyvalid for use in the home country and ACs 11, 15 are only valid for usein the HPLMN/EHPLMN). At 104, it is further tested if for at least oneof these valid Access Classes the corresponding bit in theac-BarringForSpecialAC information element contained in “AC barringparameter” information element (ac-BarringConfig in FIG. 2) is set tozero. If yes, the process proceeds at 107, if no, the process proceedsat 105. At 107, access to the cell is considered as not barred. At 105,a random number ‘rand’ uniformly distributed in the range: 0≤rand<1 isdrawn and the process proceeds at 106. At 106, it is tested if ‘rand’ islower than the value indicated by ac-BarringFactor included in “ACbarring parameter”. If yes, the process proceeds at 107, if no, theprocess proceeds at 108. As already described above, at 107, access tothe cell is considered as not barred. At 108, access to the cell isconsidered as barred and the process proceeds at 109. At 109, (access tothe cell is barred and both timers T302 and “Tbarring” are not running)a random number ‘rand’ that is uniformly distributed in the range0≤rand<1 is drawn and the process proceeds at 110. At 110, a timer“Tbarring” is started with the timer value calculated as follows, usingthe ac-BarringTime included in “AC barring parameter”:“Tbarring”=(0.7+0.6*rand)*ac-BarringTime. As described with regard to101 and 102, access to the cell is considered as barred as long as thistimer “Tbarring” is running. The timer T302 is used to delay the RRCconnection setup repetitions, and timer “Tbarring” is used as a randombackoff timer.

That is, for regular UEs with AC 0-9, the test at 104 fails. Theiraccess is controlled by ac-BarringFactor and ac-BarringTime. The UEgenerates a random number (105 in FIG. 1)—“rand” generated by the UE hasto pass the “persistent” test (106 in FIG. 1) in order for the UE toaccess. By setting ac-BarringFactor to a lower value, the access forregular ACs is restricted (UE must generate a “rand” that is lower thanthe threshold in order to access) while priority users with AC 11-15 canaccess without any restriction if the corresponding AC bit is set.

EAB, Extended Access Barring mechanism introduced for MTC devices, isalso based on access classes but also has EAB categories (a,b,c) inaddition.

NB-IoT access barring is also based on access classes. However, ACDC(Application specific Congestion control for Data Communication) whichprovides service specific access barring works on ACDC categories (16categories per PLMN) and not on ACs.

Access barring applies to the following types of calls and hasassociated barring time and factor and applied per PLMN: Emergencycalls, MO-signaling, MO-Data, MMTEL voice, MMTEL video, CSFB, andUnattended data transmission. Technically, all types listed above shouldbe applicable to MTC UEs in different coverage areas.

Coverage Enhancements

In LTE, category information is used to allow the eNB to communicateeffectively with all the UEs connected to it. The UE categories definecombined uplink and downlink capabilities. eMTC (which is also known asLTE-M) introduces coverage enhancements (CE) in category M.

Coverage enhancements can extend the range of a cell or improve signalpenetration into buildings. There are two coverage enhancement modes, CEMode A and CE Mode B. The main difference between Mode A and Mode B isthat Coverage Enhancement Mode A supports only moderate coverageenhancements whereas Mode B supports deep coverage. These two modes arespecified for RRC Connected state and they provide up to 15 dBenhancement using a variety of techniques such as subframe repetition,frequency hopping, boosting the reference symbols, and enhanced PRACH,as well as increasing transmit power. Since the two modes CE Mode A andCE Mode B are specified for RRC Connected state, they are configured bythe eNB.

As it is explained in [6], which CE mode to use may be dependent uponthe CE level (repetition level). For example: Mode A and B each supporta different maximum number of sub frame repetitions. In CE Mode A thereare no repetitions or a small number of repetitions. Operation in CEMode A would have an equivalent coverage as that of UE Category 1. Thedifference in coverage between LC-MTC and UE Category 1 due to 1 Rx, 6PRB narrowband and reduced uplink transmit power in LC-MTC iscompensated by utilizing a small number of repetitions.

In CE Mode B there are a large number of repetitions. An MTC UEoperating in CE Mode B has coverage of up to 15 dB coverage enhancementwith reference to that of UE Category 1. CE Mode B is targeted atdevices that are stationary (or with limited mobility) and insidebuildings where the assumed use case is for smart meters operating inbasements. It should be appreciated that the range of Rel-13 LC-MTCapplications is not just for stationary smart meters in basements butrather for a large range of other applications such as smart watches,wearable devices, smart sensors, etc. For applications other thanunfortunate smart meters in basements, deep coverage is unlikely to beused and moderate mobility is expected.

For example, according to [7], if the most recent PRACH CE level for theUE is 0 or 1, the contents of the Random Access Response Grant areinterpreted according to CE Mode A. If the most recent PRACH CE levelfor the UE is 2 or 3, the contents of the Random Access Response Grantare interpreted according to CE Mode B. Still further, according to [2],the preambles are contained in Random Access Preambles groups for eachCE level. That is, UEs in the same CE level use the same RACH resources.

Per CE Level ACB

It is assumed that existing techniques for access control such as ACB,EAB, or ACDC described above will work well for CE mode A. However, perCE level ACB can provide better control. So the embodiments describedbelow are related to the details of introducing “per CE level” ACB (ACBwith CE level specific parameters).

The embodiments described below introduce a possibility for the networkto broadcast per CE level access control parameters (e.g. ACB/EAB/ACDC).This approach of per CE level access barring allows the networkflexibility to e.g. allow a maximum number of UEs to access thenetwork/cell by e.g. not permitting or permitting only a low number ofdeep coverage UEs. Still further, CE level access barring may allow deepcoverage UEs, if operators are interested in creating extra revenue fromdeep coverage UEs, and in this case the network may, in case ofcongestion, bar more of the shallow coverage UEs.

An MTC UE will read the above parameters in the extended SIB2 and applybarring parameters based on its coverage level.

FIG. 2 shows an embodiment of an extended SIB2 information that includesaccess class barring parameters for per CE level access barring. TheSIB2 information includes an information element AC-BarringConfig 201.This IE AC-BarringConfig 201 includes an ac-BarringConfigLevel0 IE 202that carries access class barring parameters for CE level 0 UEs, anac-BarringConfigLevel1 IE 203 that carries access class barringparameters for CE level 1 UEs, an ac-BarringConfigLevel2 IE 204 thatcarries access class barring parameters for CE level 2 UEs, and anac-BarringConfigLevel3 IE 205 that carries access class barringparameters for CE level 3 UEs.

The ac-BarringConfigLevel0 IE 202 carries access class barringparameters for CE level 0 UEs, namely ac-BarringFactor 202-1,ac-BarringTime 202-2 and ac-BarringForSpecialAC 202-3. The IEac-BarringFactor 203-1 controls the random number test of the randomaccess procedure (105 and 106 in FIG. 1) for CE level 0 UEs. If therandom number drawn (105 in FIG. 1) by a CE level 0 UE is lower thanthis value ac-BarringFactor 202-1, access is considered as allowed bythe CE level 0 UE. Otherwise, access is considered as barred by the CElevel 0 UE. The values of ac-BarringFactor 203-1 of the type ENUMERATED{p00, p05, p10, p15, p20, p25, p30, p40, p50, p60, p70, p75, p80, p85,p90, p95} are interpreted in the range [0,1): p00=0, p05=0.05, p10=0.10,. . . , p95=0.95. The parameter ac-BarringTime 202-2 of type ENUMERATED{s4, s8, s16, s32, s64, s128, s256, s512} is used to calculate thebarring time tbarring (110 in FIG. 1). The parameterac-BarringForSpecialAC 202-3 of the type BIT STRING (SIZE(5)) is astring of 5 bits that control access of CE Level 0 UEs with AC 11-15. ACE level 0 UE that has one or more ACs with a value in the range 11 . .. 15 and for at least one of these valid ACs the corresponding AC bitcontained in ac-BarringForSpecialAC 202-3 is set will consider access tothe cell as not barred (see 104 in FIG. 1).

The ac-BarringConfigLevel1 IE 203 carries corresponding access classbarring parameters for CE level 1 UEs, namely ac-BarringFactor 203-1,ac-BarringTime 203-2 and ac-BarringForSpecialAC 203-3. Theac-BarringConfigLevel2 IE 203 carries corresponding access class barringparameters for CE level 2 UEs, namely ac-BarringFactor 204-1,ac-BarringTime 204-2 and ac-BarringForSpecialAC 204-3. Theac-BarringConfigLevel3 IE 205 carries corresponding access class barringparameters for CE level 3 UEs, namely ac-BarringFactor 205-1,ac-BarringTime 205-2 and ac-BarringForSpecialAC 205-3. Concerning thedescription of these parameters, it is referred to the above descriptionwith regard to ac-BarringConfigLevel0 202.

The design of parameters AC-BarringConfigLevel0 could by based on thecurrent specifications. For example, the same information element thatis defined in [1] and [2] as AC-BarringConfig may be used asAC-BarringConfigLevel0. The same applies for AC-BarringConfigLevel1,ACBarringConfigLevel2, and AC-BarringConfigLevel3.

For example, AC-BarringConfig as defined in [1] and [2] may be used totransport the AC Parameters for CE level 0 and three additionalinformation elements of the same structure may be added to SIB2 in orderto transport the respective AC parameters for CE levels 1, 2 and 3.

The skilled person will be aware that any deviations from thisembodiment with regard to the number of CE levels, the position of theparameters in the information elements and the precise structure of theinformation elements are within his common general knowledge. Thedisclosure is thus not limited to the specific example given above.

In the above embodiment the ACB mechanism of [1], [2] has been adaptedin view of the per CE level aspect. This disclosure is, however, notrestricted to ACB parameters. In alternative embodiments, EAB parametersare broadcast per CE level, and in yet other embodiments ACDCparameters, or any combinations of such parameters are broadcast per CElevel. In yet other embodiments only some of the access mechanisms arerealized per CE level, e.g. ACB parameters may not be broadcast per CElevel but EAB parameters are, or only ACDC parameters are broadcast perCE level.

CE Level “Reselection” and Access Class Barring

There is a problem with RSRP measurement accuracy when UE is in deepcoverage and UE may not be aware of its accurate CE level. For example,all UEs in CE mode B may judge their presence in CE level 2 as shown inFIG. 3.

FIG. 3 shows an example of an erroneous CE level judgement. Due to theabnormality of RSRP measurements some of UEs 301-1, 301-2, 301-3, 301-4,301-5 have erroneously judge their position in CE level 2 even if theactual level is CE level 3. As indicated by the dashed arrows in FIG. 3,in the given example, UEs 301-1, 301-4 and 301-5 have erroneously judgedtheir position in CE level 2. This overloads RACH resources partitionedfor CE level 2 as these preambles will be used by all UEs 301-1, 301-2,301-3, 301-4, 301-5 which judge their presence in CE level 2. If RandomAccess (RA) resource overload happens, then a backoff timer is sent inthe Random Access Response (RAR). But the RA preamble will be repeatedmany times and the probability of collision will be higher. So, it isbeneficial if the network sets access barring parameters per CE leveland dimension RA resources accordingly.

After successful RA procedure these UEs will get distributed between CElevel 2 and CE level 3. This CE level “reselection” is part of thecurrent RACH procedure as described in [2] (TS 36.321).

FIG. 4 shows the aspect of CE level “reselection” of the RACH procedureas defined in section 5.1.4 of [2] (TS 36.321). According to thisprocedure, if no Random Access Response is received within the RAResponse window, or if none of all received Random Access Responsescontains a Random Access Preamble identifier corresponding to thetransmitted Random Access Preamble, the Random Access Response receptionis considered not successful and the MAC entity proceeds as follows: At401, it is determined ifPREAMBLE_TRANSMISSION_COUNTER_CE=maxNumPreambleAttemptCE for thecorresponding enhanced coverage level+1. If this is determined to thepositive, the process proceeds at 402. At 402, thePREAMBLE_TRANSMISSION_COUNTER_CE is reset and the process proceeds at403. At 403, the MAC entity considers to be in the next enhancedcoverage level, if it is supported by the Serving Cell and the UE,otherwise the MAC entity stays in the current enhanced coverage leveland the process proceeds at 404. At 404, the MAC entity selects theRandom Access Preambles group, ra-ResponseWindowSize,mac-ContentionResolutionTimer, and PRACH resource corresponding to theselected enhanced coverage level.

According to this RACH procedure, UEs in CE level 3 will require morerepetitions compared to Rep level 2 and hence a UE in Rep level 3 willbe utilizing more radio resources than a UE in CE level 2.

FIG. 5 shows an embodiment of a modified RACH procedure. This modifiedRACH procedure is based on the RACH procedure as described in [2] (TS36.321) described above. However, if no Random Access Response isreceived within the RA Response window, or if none of all receivedRandom Access Responses contains a Random Access Preamble identifiercorresponding to the transmitted Random Access Preamble, the RandomAccess Response reception is considered not successful and the MACentity proceeds as follows: At 501, it is determined ifPREAMBLE_TRANSMISSION_COUNTER_CE=maxNumPreambleAttemptCE for thecorresponding enhanced coverage level+1. If this is determined to thepositive, the process proceeds at 502. At 502, thePREAMBLE_TRANSMISSION_COUNTER_CE is reset and the process proceeds at503. At 503, the MAX entity considers to be in the next enhancedcoverage level, if it is supported by the Serving Cell and the UE,otherwise the MAC entity stays in the current enhanced coverage leveland the process proceeds at 504. At 504, the access barring check asdescribed with regard to FIG. 1 is performed on per CE level basis andthe process proceeds at 505. If, at 505, it is determined that theaccess barring check was successful, then the process proceeds at 506.At 506, the MAC entity selects the Random Access Preambles group,ra-ResponseWindowSize, mac-ContentionResolutionTimer, and PRACH resourcecorresponding to the selected enhanced coverage level. If, at 505, it isdetermined that the access barring check was not successful, then theprocess proceeds at 507. At 507, the MAC entity waits for the barringtimer for this CE level to expire.

According to this embodiment, the access class barring parameters(ACB/EAB/ACDC) are checked when CE level changes in the UE during the RAprocedure. For example, when the UE moves from CE level 2 to CE level 3,the UE checks if it is allowed to access in CE level 3 if networkbroadcasted ACB/EAB/ACDC parameters for CE level 3. If the UE is barred,then it shall not send RA preamble and wait for barring timer for thisCE level to expire. According to this process, the UE needs to draw arandom number (105 in FIG. 1) and compare it with the broadcasted number(106 in FIG. 1).

It is assumed that the UE will not re-read SIB2 to find out new barringparameters if it changes the coverage level. The UE will acquire SIB2 inone go and apply different parameters and try to avoid decoding ofmultiple transmissions of SIB2. However, access barring may change ordifferent versions of a SIB2 or a new SIB may be broadcasted indifferent CE modes or levels. So, according to alternative embodiments,a UE may also be configured to re-acquire SIB2 for new AC parameterswhen changing CE level (or CE mode).

Access Barring Check and CE Level Change

FIG. 6 shows an embodiment of a modified access barring check. Theprocess of FIG. 6 corresponds to that of FIG. 1. At 601 it is tested iftimer T302 or “Tbarring” is running and CE level (respectively the CEmode) is unchanged. If yes, the process proceeds at 602, if no, theprocess proceeds at 603. At 602, access to the cell is considered asbarred. At 603, it is tested if SIB2 includes the information element“AC barring parameters” for the current CE level/mode. If yes, theprocess proceeds at 604, if no, the process proceeds at 607. At 604, itis tested if the UE has one or more Access Classes, as stored on theUSIM, with a value in the range 11 . . . 15, which is valid for the UEto use. At 604, it is further tested if for at least one of these validAccess Classes the corresponding bit in the ac-BarringForSpecialACinformation element contained in “AC barring parameter” informationelement for the current CE mode is set to zero. If yes, the processproceeds at 607, if no, the process proceeds at 605. The processes at605, 606, 607, 608, 609 and 610 correspond to those of FIG. 1. Accordingto this embodiment, if a UE moved from CE level 2 (CE mode B) to CElevel 1 (CE mode A) during a timespan when the barring timer has beenrunning, then the UE checks access barring parameters for CE level 1 (CEmode A) (603 in FIG. 6) and terminates the barring timer earlier (601 inFIG. 6). As, according to this embodiment, barring factor and barringtime may be different in different CE modes a the network may bar ahigher number of UEs in deep coverage (due to repetitions) rather thanin shallow coverage.

Similarly, it is also possible that the UE is barred in one CE level andhas ac-barring timer running. But then UE moves into a different CElevel and has different barring parameters or no barring. Here, the UEshould attempt the access barring check as per new parameters and stopthe ac-barring timer related to the previous CE level. The above exampleis more suitable for the case when e.g. the UE moves CE levels within CEmode A. It may not be relevant to CE mode B due to measurementinaccuracy but, in general, the procedure may apply to all CE levels.

In the embodiments described above, the barring timer is terminated whenthere is a change of the CE level. In alternative embodiments, however,the barring timer is applicable across all CE levels/modes, i.e. the MACentity waits until the barring timer has elapsed and only then tries toreconnect based on the new barring parameters of the new CE level.

Two Stage Access Class Barring Per CE Level

FIG. 7 shows an embodiment of a two stage access class barring per CElevel.

According to a first aspect of this embodiment, access class barring perCE level is applicable to RA resources only. At 701, the network checksif RA resources are overloaded. If yes, the process proceeds at 702, ifno, the process proceeds at 704. At 701, the network broadcasts accessbarring per CE level for RA resources and then proceeds at 703. At 703,the UE checks RA resource barring before initiating the RA procedure.This will allow flexibility on the network side to configure accessbarring for partitioned RA resources which are most likely to getoverloaded. This may for example avoid overload of RA resources in CElevel 2 as described above in the context of FIG. 3 by e.g. barring moreCE level 2 UEs and not barring other RA resource partitions (e.g. CElevel 0 and CE level 1).

According to a second aspect of this embodiment, if it is determined at701 that RA resources are not congested (for example because accessbarring related to RA resources has been successful) then, at 704, theUE performs the RA procedure and determines its accurate CE level anddoes not apply access barring during the RA procedure. Once the CE levelhas been determined then, at 705, the UE performs the access barringcheck for the accurate CE level before sending the RRC connectionRequest (Msg 3).

A benefit of this approach is that layer independence can be maintained.Access barring is specified in the RRC layer and the RA procedure isspecified in the MAC layer. There will be no need to modify MAC behaviorwhile introducing per CE level access barring in RRC. RRC connectionRequest (Msg 3) is an RRC message and barring can be applied in RRC. Therandom access preamble transmission to the eNB (Msg 1 transmission),which is subjected to access barring, is also triggered by RRC sublayer.However, the UE will perform RA procedure even if it should be barred.

More Accurate RSRP Measurement

As described previously, the UE's RSRP measurement is not accurate atdeep coverage, e.g. at CE Level 2 and 3 since the SNR is very low. Oneway to obtain an accurate measurement is to accumulate more CRS samplesor make use of other known signals such as PSS/SSS and PBCH.

Hence, FIG. 8 shows an embodiment in which a more accurate RSRPmeasurement is performed if the AC barring parameters are set for aparticular CE level. At 801, the UE checks if the AC barring parametersare set for a particular CE level (the current CE level of the UE). Ifyes, the process proceeds at 803, if no, the process proceeds at 802. At803, the UE switches to a more accurate measurement procedure in whichit may take longer to perform the measurement. Such a performance can bespecified in RAN4. At 802 (AC barring is not enabled) the UE revertsback to the less accurate measurement. This recognizes that without ACbarring the UE would perform PRACH ramping and move through thedifferent CE levels. However, if AC barring is enabled, the UE will notbe able to move through the different CE levels as per the embodimentabove and therefore it is beneficial to use more measurement samples(i.e. also power) to obtain a more accurate measurement.

Increased Barring Time

According to another embodiment, the TBarring parameter is increasedbeyond the value of 512 seconds currently specified in the standard ande.g. two or more additional values such as 1024s, 2048s, 4096s, 8192sare added so that network is able to bar deep coverage UEs for longertime considering repetitions. According to this embodiment, the valuerange for TBarring is enhanced for all CE levels so flexibility isprovided to the network side to barr UEs in different CE levels fordifferent time-periods, independently. However, in other embodiments,the value range of TBarring may only be enhanced for deep coverage CElevels.

CE Level Dependent Barring Time

According to yet another embodiment, the TBarring parameter is scaled upwith the CE level. For example, the formula(0.7+0.6*rand)*ac-BarringTime (610 in in FIG. 6 and correspondingdescription above) may be modified to multiply by the CE level:[(0.7+0.6*rand)*ac-BarringTime.]*CE Level (1,2,3) or any other constantvalue scaling up with the CE level.

Implementation

In the following, an embodiment of a general purpose computer 130 isdescribed under reference of FIG. 9. The computer 130 can be implementedsuch that it can basically function as any type of apparatus or entity,base station or new radio base station, transmission and receptionpoint, or user equipment as described herein. The computer hascomponents 131 to 140, which can form a circuitry, such as any one ofthe circuitries of the entities, base stations, and user equipment, asdescribed herein.

Embodiments which use software, firmware, programs or the like forperforming the methods as described herein can be installed on computer130, which is then configured to be suitable for the concreteembodiment.

The computer 130 has a CPU 131 (Central Processing Unit), which canexecute various types of procedures and methods as described herein, forexample, in accordance with programs stored in a read-only memory (ROM)132, stored in a storage 137 and loaded into a random access memory(RAM) 133, stored on a medium 140, which can be inserted in a respectivedrive 139, etc.

The CPU 131, the ROM 132 and the RAM 133 are connected with a bus 141,which in turn is connected to an input/output interface 134. The numberof CPUs, memories and storages is only exemplary, and the skilled personwill appreciate that the computer 130 can be adapted and configuredaccordingly for meeting specific requirements which arise when itfunctions as a base station, and user equipment.

At the input/output interface 134, several components are connected: aninput 135, an output 136, the storage 137, a communication interface 138and the drive 139, into which a medium 140 (compact disc, digital videodisc, compact flash memory, or the like) can be inserted.

The input 135 can be a pointer device (mouse, graphic table, or thelike), a keyboard, a microphone, a camera, a touchscreen, etc.

The output 136 can have a display (liquid crystal display, cathode raytube display, light emittance diode display, etc.), loudspeakers, etc.

The storage 137 can have a hard disk, a solid state drive and the like.

The communication interface 138 can be adapted to communicate, forexample, via a local area network (LAN), wireless local area network(WLAN), mobile telecommunications system (GSM, UMTS, LTE, etc.),Bluetooth, infrared, etc.

It should be noted that the description above only pertains to anexample configuration of computer 130. Alternative configurations may beimplemented with additional or other sensors, storage devices,interfaces or the like. For example, the communication interface 138 maysupport other radio access technologies than the mentioned UMTS and LTE.

When the computer 130 functions as a base station, the communicationinterface 138 can further have a respective air interface (providinge.g. E-UTRA protocols OFDMA (downlink) and SC-FDMA (uplink)) and networkinterfaces (implementing for example protocols such as S1-AP, GTP-U,S1-MME, X2-AP, or the like). Moreover, the computer 130 may have one ormore antennas and/or an antenna array. The present disclosure is notlimited to any particularities of such protocols.

The methods as described herein are also implemented in some embodimentsas a computer program causing a computer and/or a processor and/or acircuitry to perform the method, when being carried out on the computerand/or processor and/or circuitry. In some embodiments, also anon-transitory computer-readable recording medium is provided thatstores therein a computer program product, which, when executed by aprocessor/circuitry, such as the processor/circuitry described above,causes the methods described herein to be performed.

It should be recognized that the embodiments describe methods with anexemplary ordering of method steps. The specific ordering of methodsteps is, however, given for illustrative purposes only and should notbe construed as binding.

It should also be noted that the division of the control or circuitry ofFIG. 9 into units 131 to 140 is only made for illustration purposes andthat the present disclosure is not limited to any specific division offunctions in specific units. For instance, at least parts of thecircuitry could be implemented by a respective programmed processor,field programmable gate array (FPGA), dedicated circuits, and the like.

All units and entities described in this specification and claimed inthe appended claims can, if not stated otherwise, be implemented asintegrated circuit logic, for example on a chip, and functionalityprovided by such units and entities can, if not stated otherwise, beimplemented by software.

In so far as the embodiments of the disclosure described above areimplemented, at least in part, using software-controlled data processingapparatus, it will be appreciated that a computer program providing suchsoftware control and a transmission, storage or other medium by whichsuch a computer program is provided are envisaged as aspects of thepresent disclosure.

Note that the present technology can also be configured as describedbelow.

(1) An apparatus comprising circuitry configured to perform a RandomAccess procedure that is based on one or more access control parameters(AC-BarringConfigLevel0, ACBarringConfigLevel1, AC-BarringConfigLevel2,AC-BarringConfigLevel3) that are specific for a predefined coveragelevel (CE level 0, CE level 1, CE level 2, CE level 3).

(2) The apparatus of (1), wherein the circuitry is configured toreceive, for one or more predefined coverage levels (CE level 0, CElevel 1, CE level 2, CE level 3), one or more access control parameters(AC-BarringConfigLevel0, AC-BarringConfigLevel1, AC-BarringConfigLevel2,ACBarringConfigLevel3) that are specific for the respective coveragelevel.

(3) The apparatus of (1) or (2), wherein the circuitry is configured toapply the coverage-specific access control parameters(AC-BarringConfigLevel0, AC-BarringConfigLevel1, ACBarringConfigLevel2,AC-BarringConfigLevel3) based on its coverage level (CE level 0, CElevel 1, CE level 2, CE level 3).

(4) The apparatus of anyone of (1) to (3), wherein the circuitry isconfigured to determine its coverage level (CE level 0, CE level 1, CElevel 2, CE level 3) by measurement (RSRP).

(5) The apparatus of anyone of (1) to (4), wherein there are fourpredefined coverage levels (CE level 0, CE level 1, CE level 2, CE level3) and/or there are two predefined coverage modes (CE mode A, CE modeB).

(6) The apparatus of anyone of (1) to (5), wherein a barring time(tbarring) depends on the coverage level.

(7) The apparatus of anyone of (1) to (6), wherein the circuitry isconfigured to perform a modified Random Access (RA) procedure inenhanced coverage and to take coverage level specific access barringparameters into account.

(8) The apparatus of anyone of (1) to (7), wherein the coverage-specificaccess control parameters (AC-BarringConfigLevel0,AC-BarringConfigLevel1, AC-BarringConfigLevel2, ACBarringConfigLevel3)comprise a coverage-specific barring factor (ac-BarringFactor), acoverage-specific barring time (ac-BarringTime), and/orcoverage-specific access class bits (ac-BarringForSpecialAC).

(9) The apparatus of anyone of (1) to (8), wherein the circuitry isconfigured to perform a coverage level reselection process.

The apparatus may for example perform the coverage level reselectionprocess if no Random Access Response is received within the RA Responsewindow, or if the Random Access Response reception is considered notsuccessful.

(10) The apparatus of (9), wherein the circuitry is configured toperform an access barring check for a specific coverage level within acoverage level reselection process.

(11) The apparatus of (10), wherein the circuitry is configured toperform the access barring check when the coverage level changes duringa Random Access procedure.

(12) The apparatus of anyone of (10) or (11), wherein the circuitry isconfigured to, if the access barring check for the specific coveragelevel is not successful, wait for the barring timer for this coveragelevel to expire.

(13) The apparatus of anyone of (10) to (12), wherein the circuitry isconfigured to, if the access barring check for the specific coveragelevel is successful, select a Random Access Preambles group, a ResponseWindow Size, a Contention Resolution Timer, and/or a PRACH resourcecorresponding to the selected enhanced coverage level.

(14) The apparatus of anyone of (10) to (13), wherein the access barringcheck is performed on the MAC layer.

(15) The apparatus of anyone of (1) to (14), wherein the circuitry isconfigured to terminate a barring timer when the coverage level changes.

(16) The apparatus of anyone of (1) to (15), wherein the circuitry isconfigured to perform RA access barring and, if successful, then performother resource barring.

(17) The apparatus of (16), wherein RRC and MAC layer independence ismaintained.

(18) The apparatus of anyone of (1) to (17), wherein the circuitry isconfigured to perform a more accurate RSRP measurement if AC barringparameters are set for a particular coverage level.

(19) The apparatus of anyone of (1) to (18), wherein the apparatus is auser equipment.

(20) An apparatus comprising circuitry configured to broadcast accesscontrol parameters that are specific for a predefined coverage level.

(21) The apparatus of (20), wherein the circuitry is configured tochoose the access control parameters such that coverage level accessbarring prefers deep coverage UEs over shallow coverage UEs.

(22) The apparatus of (20) or (21), wherein the circuitry is configuredto apply coverage-specific access class barring to RA resources only.

(23) The apparatus of anyone of (20) to (22), wherein the apparatus is anetwork entity such as a base station.

(24) Method comprising performing a Random Access (RA) procedure that isbased on one or more access control parameters (AC-BarringConfigLevel0,AC-BarringConfigLevel1, ACBarringConfigLevel2, AC-BarringConfigLevel3)that are specific for a predefined coverage level (CE level 0, CE level1, CE level 2, CE level 3).

(25) Computer program including instructions, the instructions whenexecuted on a processor performing a Random Access (RA) procedure thatis based on one or more access control parameters(AC-BarringConfigLevel0, AC-BarringConfigLevel1, AC-BarringConfigLevel2,ACBarringConfigLevel3) that are specific for a predefined coverage level(CE level 0, CE level 1, CE level 2, CE level 3).

(26) A non-transitory computer-readable recording medium that storestherein a computer program product, which, when executed by a processor,causes the method according to (24) to be performed.

Abbreviations

-   3GPP 3rd Generation Partnership Project-   LTE Long Term Evolution-   M2M Machine to Machine-   IE Information Element-   LTE-M LTE M2M-   VoLTE Voice over LTE-   IoT Internet of Things-   MTC Machine-type Communication-   mMTC massive MTC-   NB-IoT NarrowBand IoT (Release-13)-   eNB-IoT enhanced NB-IoT (Release-14)-   eMTC enhanced MTC (Release-13)-   feMTC further enhanced MTC (Release-14)-   efeMTC even further enhanced MTC (Release-15)-   MMTEL Multimedia Telephony Service-   UE User Equipment-   UL Uplink-   ACB Access Class Barring-   EAB Extended Access Barring-   ACDC Application specific Congestion control for Data Communication-   CE Coverage Enhancement-   MAC Medium Access Control-   RRC Radio Resource Control-   SIB System Information Block-   MO Mobile Originating-   MT Mobile Terminating-   PRACH Physical Random Access Channel-   PBCH Physical Broadcast Channel-   RA Random Access-   RAR Random Access Response-   RSRP Reference Signal Received Power-   PSS Primary synchronization signal-   SSS Secondary synchronization signal

REFERENCES

-   [1] 3GPP TS 36.331 v14.2.1, “Evolved Universal Terrestrial Radio    Access (E-UTRA); Radio Resource Control (RRC); Protocol    specification”-   [2] 3GPP TS 36.321 v14.2.0, “Evolved Universal Terrestrial Radio    Access (E-UTRA); Medium Access Control (MAC) protocol specification”-   [3] 3GPP TS 22.011 v15.0.0, “Service accessibility”-   [4] 3GPP TS 23.122 v14.2.0, “Non-Access-Stratum (NAS) functions    related to Mobile Station (MS) in idle mode”-   [5] 3GPP TS 36.213 V14.2.0, “Evolved Universal Terrestrial Radio    Access (E-UTRA); Physical layer procedures”-   [6] 3GPP R1-156979: “On CE Mode Capability of eMTC”, Sony-   [7] 3GPP RP-170732: “New WID on Even further enhanced MTC for LTE,”    Ericsson, Qualcomm-   [8] 3GPP RP-170852: “Further NB-IoT enhancements”, Huawei

1. An apparatus, comprising: circuitry configured to perform a RandomAccess procedure that is based on one or more access control parametersthat are specific for a predefined coverage level. 2-3. (canceled) 4.The apparatus of claim 1, wherein the circuitry is further configured toreceive, for one or more predefined coverage levels, one or more accesscontrol parameters that are specific for the respective coverage level.5. The apparatus of claim 1, wherein the circuitry is further configuredto apply the coverage specific access control parameters based on itscoverage level.
 6. The apparatus of claim 1, wherein the circuitry isfurther configured to perform a coverage level reselection process. 7.The apparatus of claim 6, wherein the circuitry is further configured toperform an access barring check for a specific coverage level within thecoverage level reselection process.
 8. The apparatus of claim 7, whereinthe circuitry is further configured to perform the access barring checkwhen the coverage level changes during a Random Access procedure.
 9. Theapparatus of claim 6, the circuitry is further configured to in responseto a determination that no Random Access Response is received within aRandom Access Response window or in response to a determination thatnone of all received Random Access Responses contains a Random AccessPreamble identifier, determine that the Random Access Response receptionwas not successful.
 10. The apparatus of claim 9, wherein the circuitryis further configured to determine whether the apparatus is in a nextenhanced coverage level or whether the apparatus remains in a currentenhanced coverage level.
 11. A method, comprising: performing a RandomAccess procedure that is based on one or more access control parametersthat are specific for a predefined coverage level.
 12. The method ofclaim 11, further comprising: receiving, for one or more predefinedcoverage levels, one or more access control parameters that are specificfor the respective coverage level.
 13. The method of claim 11, furthercomprising: applying the coverage specific access control parametersbased on its coverage level.
 14. The method of claim 11, furthercomprising: performing a coverage level reselection process.
 15. Themethod of claim 14, further comprising: performing an access barringcheck for a specific coverage level within the coverage levelreselection process.
 16. The method of claim 15, further comprising:performing the access barring check when the coverage level changesduring a Random Access procedure.
 17. The method of claim 14, furthercomprising: in response to a determination that no Random AccessResponse is received within a Random Access Response window or inresponse to a determination that none of all received Random AccessResponses contains a Random Access Preamble identifier, determining thatthe Random Access Response reception was not successful.
 18. The methodof claim 17, further comprising: determining whether the apparatus is ina next enhanced coverage level or whether the apparatus remains in acurrent enhanced coverage level.
 19. A non-transitory computer-readablestorage medium storing computer-readable instructions thereon which,when executed by a computer, cause the computer to perform a method, themethod comprising: performing a Random Access procedure that is based onone or more access control parameters that are specific for a predefinedcoverage level.
 20. The non-transitory computer-readable medium of claim19, further comprising: receiving, for one or more predefined coveragelevels, one or more access control parameters that are specific for therespective coverage level.
 21. The non-transitory computer-readablemedium of claim 19, further comprising: performing a coverage levelreselection process.
 22. The non-transitory computer-readable medium ofclaim 19, further comprising: performing an access barring check for aspecific coverage level within the coverage level reselection process.